1. Field of the Invention
The present invention relates to a moving object detecting system for effectively detecting a moving object in a given environment from environmental image frames momently obtained by a mobile imaging system incorporated in a moving unit such as a mobile robot.
2. Description of the Related Art
One of the important techniques for realizing a state monitor apparatus, a mobile robot, or the like is a technique for detecting a moving object in a given environment from environmental image frames from moment to moment obtained by an imaging system which is movable. This technique for detecting the moving object from a moving image is based on a so-called motion analysis. In recent years, extensive studies have been made on this detection technique in the field of computer vision. This technique, however, is not applied to practical apparatuses or field works.
Image processing for detecting such a moving object is called a gradient-based scheme for generally detecting spatial and temporal changes in image densities of moving image frames as an object of interest. In addition to this scheme, a feature-based scheme is available in which features such as edges of a moving image (i.e., an object of interest) are extracted, and these features are correlated to each other between image frames having a time difference, thereby estimating a displacement and hence detecting the moving object.
Although the former scheme, i.e., the gradientbased scheme has an advantage in that a fine displacement can be attained with respect to the entire image, since spatial and temporal changes in image densities are detected by differentiations, detection precision is greatly degraded in the presence of noise in the image. In addition, in principle, accurate estimation values cannot be obtained in a region having a small change in density or a boundary region of the object.
To the contrary, in the latter scheme, i.e., the feature-based scheme, although portions of interest subjected to displacement measurements are dispersed in a distribution since features in an image are used, a problem such as degradation of detection precision caused by noise can be greatly reduced. In the feature-based scheme, it is not easy to correlate the features to each other between image frames having a time difference. This correspondence processing requires a long period of time if it is accurately performed in accordance with its theory. For this reason, the moving object in an environment monitored by a moving image cannot be detected at high speed.
In the conventional image processing techniques, the moving object in its environment cannot be accurately detected at high speed from image frames momently detected by a mobile imaging system.